Thermostatic unit



J. J. MCMAHON THERMOSTATIG UNIT Filed Dec. 19, 1939 Jan. 27, 1942.

,fnwen'or kwh LA Patented Jan. 27, 1942 2.271.020 r 'rnEaMosTATrc UNrr 'Joseph J. McMahon,

Lowell, Mass., assignor to Clifford Manufacturing Co., Boston. Mass., a corporation o! Delaware Application December 19, 1939, Serial No. 310,005 1 Claim. `((Jl. 297-8) The present invention relates to thermostatic units, and is more particularly concerned with sealed units embodying a diaphragm or its equiv aient and filled with thermostatic fluid which may be in the nature o! a saturated vapor to control by expansion and contraction of the diaphragm a switch, valve or other outside element in accordance with temperature variations at a point which may be more or less remote from the actuating apparatus itself.

Units of this character invariably employ a capillary in connection with the diaphragm unit, the combination of the two elements providing a sealed space, and the capillary affording communication between the diaphragm and the region to be controlled. By virtue of this construction the actual controlled valve or switch may be located where most convenient regardless of the location of the controlled region. This type of apparatus finds employment in the control of cooking ovens, refrigerators and the like. Diiiiculty has invariably been experienced in the past in providing a union between the capillary and the diaphragm or housing within which the diaphragm is contained of such a character that the capillary would withstand the rough uses to which it is subiected without premature breakage and destruction ofthe unit.

It is accordingly the purpose and object of the present invention to reorganize and improve constructions of this character in such a manner that the general construction of unit shall be free from the weaknesses which have heretofore been present.

With this and other objects in view, the various features of the invention consist incertain novel features of construction, combinations and arrangements of parts hereinafter described and claimed, the advantages oi' which will he obvious to those skilled in the art from the following descrlption.

In the accompanying drawing illustrating the preferred form of the invention, Fig. 1 represents a bottom plan view oi a diaphragm-containing housing with attached capillary; Fig. 2 is a section in elevation of the housing shown in Fig. l with a capillaryl extending therefrom; Fig. 3 is a section similar to Fig. .2 of a slightly modified form of structure: and Fig, 4 is a detail illustrating a section upon the line l-l of Fig. 1, showing the method of supporting and connecting the capillary to the bottom of the housing.

As shown in the illustrated embodiment of the invention, the unit comprises essentially a drawn metal housing I0, generally cup-shaped and having a flat bottom portion l2 and a peripheral side wall M terminating in an attaching flange I6, having openings ill for the use of attaching bolts, screws` or the like. The housing may preferably 5 be drawn from sheet metal, and is provided adjacent the open end with a peripheral seating shoulder I9, as indicated more particularly in Fig. 2. The diaphragm unit assembled within the housing may take the form o! a4 bellows 20, havl ing one integrally closed end 22, and provided with a radial attaching flange 2l at its open end which engages with the seating shoulder I9. The unit is anchored to the housing at its open end through a head 26 seated at its margin upon l the shoulder I8 and soldered thereto to permanently anchor the bellows or diaphragm therein. This head closes the normally open end of the housing, and is provided at its central portion with an opening 28 surrounded by a depressed portion 30 of the head for a purpose to be presently described.

The opposite or movable end of the bellows unit is drawn inwardly at 82, and has connected thereto a head 3l internally threaded at l5 and receiving a threaded pin 3B which extends outwardly beyond the head and is employed as an actuator for the engagement of an outside element such as the movable part of a switch or valve (not shown). In order to prevent the en- 30 trancev of solder, tinning compound or the like within the space inside of the bellows unit and beneath the cap. it will be noted that the head is provided with a shoulder 36v normally seating upon the surface 30 to limit the outward movement of the pin. The space therewithin may be sealed, it desired. by a compressible gasket l0, as indicated in Fig. 2. The botwm o! the cupshaped unit, as indicated. may be pierced at 42 with an inwardly directed opening having a sur- 40 rounding sleeve 44. The bottom is also provided with a generally U-shaped protubcrance l, as shown more particularly in Fig. 1, which closely surrounds the opening 42 at the base of the U. the legs o1' the U extending from the opening 45 across the bottom of the peripheral edge thereof,

' forming essentially a channel or trough 48, the bottom of which may be flush with the plane of the cup bottom, and which receives and lits a capillary throughout a substantial portion of 50 its length, as again indicated in Figs. l and 2.

the end of the capillary being turned angularly with relation to this portion and extending through the opening 42 at 52. The capillary is bonded to the cup by a solder material indicated 5f generally at 62, which is directed against the bottom of the cup, flows into the space between the capillary and the central opening, and also throughout the length o! the trough I8 encompassing the capillary. This construction has been found exceedingly desirable. as it permits the capillary to befbonded rigidly to the ilxed housing without liability oi breakage. and furthermore permits the employment oi a soft low temperature solder due to the area ot engagement which does not iniuriously anneai the material ot the capillary in the soldered region.

The capillary may have any appropriate length desired and depending upon the remoteness of the control region, and is lled, together with the space B0 inside of the housing and surrounding the diaphragm. with a suitable thermostatic fluid, the whole interior space having been first exhausted of air as is usual in this type of apparatus. After evacuating and sealing. the open end of the capillary through which the iluld is introduced is crimped at U3 and closed by solder, as indicated at 8l.

It will be noted that the construction shown in Fig. 3 represents a slight modification of the structure shown in Figs. l and 2. In this structure the housing shown at III is slightly less in depth and is providedl with a smaller bellows unit 12. The bellows unit is anchored to the housing in the same manner as previously described, and the movable end of the unit is thrown inwardly a sufficient depth to provide an actuator button 14, which extends through the attached head 1I, this button taking the place or the pin Il previously described. The formation oi' the bottom of the housing and the attachment oi the capillary thereto is identical with that described in Figs. l and 2, the bottom being provided with a central opening 'I8 and a generally radial trough 80 Within which the capillary 82 is received.

What is claimed is:

In a thermostatic unit, a generally cup-shaped metal housing having bottom and peripheral walls, a exible diaphragm unit cooperating with said bottom and peripheral walls to provide Va closed space within said housing, an aperture in said bottom wall, the metal of said bottom wall being formed to provide a trough-like depression oi' arcuate cross-section extending from said aperture to the periphery of said bottom wall, a capillary extending through said aperture and along the bottom oi said trough-like depression, said depression having a diameter substantially equal to the external diameter of said capillary, and solder material partially overlying said capillary throughout the length oi' said depression to retain said capillary within said depression and to seal said aperture around said capillary.

JOSEPH J. MCMAHON. 

